$(document).ready(function() {   
  //get provinces   
  $.get("getcontent.php", {category:'province'},   
    function(data) {   
      $('#province').html(data);   
  });   
  
  //get citys   
  $.get("getcontent.php", {category:'city'},   
    function(data) {   
      $('#city').html(data);   
    });   
  
    //province onchange   
    $('#province').change(function() {   
      var province = $(this).val();   
      $.get("getcontent.php", {category:'city', province:province}, function(data) {   
        $('#city').html(data);   
      });   
    });   
  
});   